class_docstr: Oscillation of a given data around another data
  
  Datas:
    This indicator can accept 1 or 2 datas for the calculation.
  
    - If 1 data is provided, it must be a complex "Lines" object (indicator)
      which also has "datas". Example: A moving average
  
      The calculated oscillation will be that of the Moving Average (in the
      example) around the data that was used for the average calculation
  
    - If 2 datas are provided the calculated oscillation will be that of the
      2nd data around the 1st data
  
  Formula:
    - 1 data -> osc = data.data - data
    - 2 datas -> osc = data0 - data1
code: def _plotinit(self):
      try:
          lname = self.dataosc._getlinealias(0)
          self.plotlines._0._name = lname + "_osc"
      except AttributeError:
          pass
  
file_path: backtrader/backtrader/indicators/oscillator.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import sys
  from .None import Indicator, MovingAverage
label_desc: Use image node_id 1 for calling the Oscillator obj's underlying member method code with example usage: obj._plotinit() without return types